The Union Special Corporation Model 35800 High Speed Feed Off-The-Arm machine is used to produce felled seams on medium to heavy weight denim. This machine, is used to produce either double felled or single fell seams. The Model 35800 High Speed Feed Off-The-Arm machine has three needles and three loopers and produces three rows of Type 401 stitches. In addition to the conventional feed dogs and presser foot, this machine includes a driven upper feed roller that engages the upper surface of the fabric behind the stitch forming area and functions to pull the fabric in the direction of feed.
When using this machine to produce a double felled seam along the inseam of denim jeans or for piecing sleeves on denim jackets, a feller assembly is located forward of the stitch forming area to assist the operator in interlapping the marginal edges of the upper and lower plies of fabric.
Denim is made from large yarns and is a "twill" type fabric that easily stretches. This characteristic of denim is the reason that jeans are so comfortable to wear. However, this characteristic of denim also makes denim difficult to sew. When sewing denim fabric the fabric should be in its natural relaxed state rather than in a stretched state. If denim is sewn when it is stretched, the seam will become distorted when the fabric attempts to return to its relaxed state.
When producing inseams on denim jeans, the operator must use her or his fingers to manually push the interlaped fabric into the stitch forming area of the sewing machine. This is necessary to assure that the fabric is being stitched in its natural relaxed state and also to assure even margins along the felled seam. The production of acceptable inseams on denim jeans requires a highly skilled operator who is experienced and who has been extensively trained. When producing the inseam on denim jeans when the cross seam is encountered, the number of fabric plies abruptly quadruples. A double felled seam has four plies of material, however, when four double felled seams converge at a point, as occurs at the crouch of a pair of denim jeans, sixteen plies of material must be sewn together. Pushing the fabric into the stitch forming area when cross seams are encountered is particularly stressful on the fingers and hands of the sewing machine operator. Furthermore, if the operator must concentrate her or his attention and efforts on pushing the fabric into the stitch forming area, their attention to other facets of the operation is diminished and it becomes more likely that the fabric will not be properly fed into the feller attachment. For the foregoing reasons, there is a need for a machine that can relieve the sewing machine operator of the manual and stressful task of pushing the folded fabric into the stitching area of the sewing machine.